To calculate the cross product between vectors A and B, first we need to represent the matrices as vectors in R^3:
A = (1, 3, 2)
B = (1, 2, -1)
Now, we can calculate the cross product A x B manually using the formula:
A x B = ((A2B3 - A3B2), -(A1B3 - A3B1), (A1B2 - A2B1))
Substitute the values into the formula:
A x B = (3*-1 - 22, -(1-1 - 21), (12 - 3*1))
A x B = (-3 - 4, -(-1 - 2), (2 - equals (-7, 3, -1).